The constitutional question

• The Constitution says the president "shall have the Power to grant Reprieves and Pardons for offenses against the United States, except in Cases of Impeachment."
• The clear exceptions: The president's pardon power is limited to only federal crimes because of the specificity of "offenses against the United States." And most legal experts say a pardon can not be used on any "future" crimes, according to Politifact.
• But, but, but: The Constitution only explicitly prevents the president from pardoning himself in cases of impeachment, so any other instances are an open question.

The "yes" crowd

• John Yoo, a law professor at Berkeley and former legal adviser in the George W. Bush administration, wrote in The New York Times that "President Trump can clearly pardon anyone — even himself — subject to the Mueller investigation."
• David Rivkin Jr. and Lee Casey, former staffers in the Reagan and H.W. Bush administrations, wrote in The Wall Street Journal that Trump could "end this madness by immediately issuing a blanket presidential pardon to anyone involved in supposed collusion with Russia or Russians during the 2016 presidential campaign." They specified that any theoretical blanket pardon would include Trump himself, provided the House did not choose to impeach him.
• P.S. Ruckman, a legal professor at Rock Valley College, kept it simple, telling Bloomberg that Trump "could write his pardon down on a napkin and sign it — that would be a pardon."

The "no" crowd

• Then-Acting Assistant Attorney General Mary Lawton wrote during the Watergate scandal: "Under the fundamental rule that no one may be a judge in his own case, the President cannot pardon himself." This is one of the most heavily-cited opinions against a presidential self-pardon, highlighted again this morning by Sen. Ed Markey (D-Mass.).

• Laurence Tribe, a professor of constitutional law at Harvard Law School, Richard Painter, the former chief White House ethics lawyer for W. Bush, and Norman Eisen, former chief White House ethics lawyer for Obama, wrote a piece for the Washington Post, titled simply: "No, Trump can’t pardon himself. The Constitution tells us so."
• Author and Michigan State law professor Brian Kalt told CNN that that the chances of a president being able to pardon himself would be less than 50%, but not 0%. He said he believes that "any court faced with the issue should rule against self-pardons' validity. But "should" and "would" are two different things."

Be smart: The even bigger question is whether Republicans would move to impeach Trump should he ever decide to issue a self-pardon. As Axios' Jim VandeHei wrote about the president's sway on his own party: "If you think he won't try something unprecedented — and maybe get away with it, at least with Republicans — you aren’t paying attention."

Go deeper: It's not normal: Trump’s obstruction and pardon moves.